Many vehicles, such as golf cars, include a ground speed governor system for limiting the degree of throttle to correspondingly limit the speed at which the vehicle may travel. Typically, these vehicles include an engine, a transmission, and a drive axle receiving drive torque from the engine through the transmission. Generally, ground speed governor systems include a plurality of weights disposed about an input shaft of the drive axle, which are configured to pivot away from the input shaft because of the centrifugal forces generated by the angular velocity of the input shaft. The weights pivot outward against a set of sliding spacers, which in turn actuate a ground speed governor shaft extending inside the drive axle. As the angular velocity of the input shaft increases so does the centrifugal force resulting in a torque produced through the ground speed governor shaft. Thus, the torque produced through the ground speed governor shaft is linear and directly proportional to the angular velocity of the input shaft.
A ground speed control mechanism, or governor system, is provided to limit the maximum vehicle speed. Traditional ground speed governor systems include a control arm with a spring assembly, an accelerator cable input interconnecting the accelerator pedal, and a throttle output interconnecting the throttle. The spring assembly includes a threaded rod, a pivot bracket, a compression spring, spring retainers, and an adjustment nut. The governed speed is preset by the manufacturer by adjusting the compression of the spring with the adjustment nut.
When the accelerator pedal is actuated, the accelerator cable pulls on the spring, which in turn applies a force to the control arm. The control arm then rotates and actuates the throttle linkage to open the throttle. As the accelerator is depressed and the vehicle accelerates, the torque exerted on the control arm by the ground speed governor shaft correspondingly increases. When this torque becomes greater than that produced by the spring assembly, the control arm rotates, compressing the spring further, thereby relieving the throttle linkage to enable closure of the throttle. As the vehicle slows, the torque exerted on the control arm by the ground speed governor shaft correspondingly decreases, enabling the control arm to rotate, thereby actuating the throttle linkage to again open the throttle. The result is a relatively constant vehicle speed, regardless of load.
Separately, small engines such as those discussed above often suffer from engine idle speed problems. For example, when the vehicle is traveling quickly and the accelerator pedal is released, occasionally the engine speed can drop rapidly causing the engine to stall. To overcome this problem, attempts have been made to use an engine idle speed governor. However, traditionally it has been necessary to choose between using a ground speed governor system or an engine idle speed governor system as each was mutually exclusive relative to the other—each attempting to actuate the throttle in an opposite direction. However, it is readily apparent that having the ability to governor both the vehicle ground speed and the engine idle speed is desirable in many applications.
Therefore, it is desirable in the industry to provide an improved governor system capable of governing both the ground speed of the vehicle to prevent over-speeding of the vehicle and the engine speed to prevent stalling of the engine. The improved governor system should be simple in construction, having a reduced number of components over traditional governor systems, for alleviating the disadvantages associated therewith.